function Map(){
    this.container = new Object();
}


Map.prototype.put = function(key, value){
    this.container[key] = value;
}


Map.prototype.get = function(key){
    return this.container[key];
}


Map.prototype.keySet = function() {
    var keyset = new Array();
    var count = 0;
    for (var key in this.container) {
// 跳过object的extend函数
        if (key == 'extend') {
            continue;
        }
        keyset[count] = key;
        count++;
    }
    return keyset;
}


Map.prototype.size = function() {
    var count = 0;
    for (var key in this.container) {
// 跳过object的extend函数
        if (key == 'extend'){
            continue;
        }
        count++;
    }
    return count;
}


Map.prototype.remove = function(key) {
    delete this.container[key];
}


Map.prototype.toString = function(){
    var str = "";
    for (var i = 0, keys = this.keySet(), len = keys.length; i < len; i++) {
        str = str + keys[i] + "=" + this.container[keys[i]] + ";\n";
    }
    return str;
}